<!DOCTYPE html><!--文档说明:告诉浏览器使用HTML5解析-->
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>/*类选择器.*/
    #h3-1 {
        color: green;
    }

    .c1 {
        color: blue;
    }

    #h3-1,.c1{
        background-color:dodgerblue;
    }
    /*属性选择器*/
    input[type = 'text']{color: green}
    /*任意元素选择器*/
    *{border: 1px solid red}
    </style>
</head>
<body>
<input type="text">
<input type="password">
<h3 id="h3-1">香蕉</h3>
<h3>苹果</h3>
<h3 class="c1">葡萄</h3>
<p>冰箱</p>
<p>洗衣机</p>
<p class="c1">电视机</p>
</body>
</html>